JPH0210942A - Loop communication system - Google Patents

Abstract

PURPOSE:To cope with lots of control information quickly and to facilitate the processing at the outgoing and reception side by providing the access system monopolying a channel till the end of transmission of control information and the access system limiting monopolization of a channel to one loop only. CONSTITUTION:A control channel transmission reception control section 50 always monitors a channel, an idle/occupied information area of a packet format is occupied and a destination information area represents its own station, then the reception processing is applied. That is, a packet is copied to reception buffers 60-1, 60-2, the presence of reception information is informed to a CPU 70 to complete the reception. Moreover, the CPU 70 stores transmission information to transmission buffers 60-4, 60-5 in the transmission to give a transmission request to a control section 50. The control section 50 applies the transmission process to send the transmission information to a channel when an idle packet is detected. Then an idle/occupied information area of a channel where a sender information area of a packet format represents its own station is made idle. That is, the control channel circulated through a loop once is released.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Field of Industrial Application) The present invention relates to a loop communication system adapted to a large-scale network.

(Prior Art) With the development of information processing technology, various systems have been developed in which a plurality of distributed information processing devices are interconnected and information is transmitted between these information processing devices. Moreover, recent trends call for the development of large-scale, sophisticated networks that integrate or combine various independently existing information transmission systems to enable even more advanced information processing.

In order to meet such demands, a loop communication system in which stations are connected in a loop via transmission lines, as shown in FIG. 9, for example, is attracting attention. The loop communication system shown in the figure includes a control station 1 and a plurality of stations 3-1, ... 3-m.
are connected in a loop via a transmission line. Terminal devices such as a computer and a FAX are connected to the control station 1 and each of the stations 3-1, . . . 3-m, and communication is performed between these terminal devices.

FIG. 10 is a diagram showing an example of a frame format used in communication in the system shown in FIG. 9, etc.

The frame 7 shown in the figure consists of a frame synchronization area 9, a control area 11, and a data communication area 13.

The frame synchronization area 9 indicates the beginning of the frame. The control area 11 is an area for transmitting and receiving control information between the control station and each station. The data communication area 13 is composed of a plurality of time slots. Communication is performed using time slots as communication paths between terminals accommodated in each station.

The control information sent and received between each station using the control area 11 includes control information between stations such as failure information of the station and information on instructions to the station regarding the failure, and circuit switching system terminals accommodated in each station. connection control information, etc. between

(Problem to be Solved by the Invention) If the above control information is frequently transmitted and received, the probability that the control area is in use increases, leading to a reduction in system throughput. Therefore, it is conceivable to divide the control region into a plurality of channels.

In other words, since each station can communicate individually using a plurality of channels, the pipe in the control area can be made substantially thicker.

When considering only the transfer of control information, it is advantageous to set the band of one channel so that the longest amount of control information can be transmitted and received at one time in order to process a large amount of control information.

However, this only holds true when the speed of the transmission path can be set to a very wide band, and in general, the bandwidth of the transmission path has a technical upper limit, and the bandwidth of one frame is similarly considered to be finite. There must be.

That is, expanding the control area of a frame with a finite band narrows the band of the data communication area, leading to a reduction in the communicable capacity of the entire system.

Therefore, for example, by setting the band of one channel to be smaller than the maximum value of the control information, the usage efficiency of the transmission path can be improved to some extent. Furthermore, control information sent and received between terminals is generally longer than control information sent and received between stations. If the amount of information differs depending on the type of control information as described above, by setting multiple channels in different bands, it is possible to further improve the usage efficiency of the transmission path.

Furthermore, setting the channel band smaller than the maximum value of the control information to be transmitted requires that the control information be divided into a plurality of packets and transmitted as described above.

Therefore, depending on the amount of control information (data length),
It is possible that the order of reception may be disrupted.

In other words, if a packet with a long data length is divided into multiple packets and received from one station, and a packet is received from another station, data from different sources will be mixed on the receiving side. . When separating this mixed data, there are problems such as a very complicated procedure and circuit.

The present invention was made in response to these circumstances, and its purpose is to provide a loop communication method that efficiently utilizes control information, provides fast response to devices connected to the system, and is adaptable to large-scale networks. Our goal is to provide the following.

[Structure of the Invention] (Means for Solving the Problems) In other words, in the loop communication system of the present invention, a control station and a plurality of stations are connected in a loop via a transmission path, and a control area and a plurality of time slots are connected. A frame having a data communication area divided into two is circulated on the transmission path, a control information packet is transmitted between the stations using the control area, and a time slot of the data communication area is accommodated in each station. In a loop communication method that performs allocated data communication as a communication path between terminals, the control area is
Split into multiple channels of the same band or different bands,
The present invention is characterized by having two types of access methods: an access method in which the channel is exclusively used until the transfer of the control information is completed, and an access method in which the exclusive use of the channel is limited to one loop.

(Function) In the loop communication method of the present invention, the control area is divided into a plurality of channels, and an access method in which the channel is exclusively used until the transfer of control information is completed, and an access method in which the exclusive use of the channel is limited to one round of the loop. Since it has two types of access methods, it is possible to quickly deal with a large amount of control information, it is easy to process on the sending and receiving sides in terms of order, and it is possible to use the control area efficiently. can. Furthermore, since the band of each control channel can be set individually, it can be applied to a system in which the amount of information varies depending on the type of control information.

Therefore, a highly practical system suitable for large-scale networks can be realized.

(Example) Hereinafter, details of an example of the present invention will be described based on the drawings.

The configuration of the loop communication system in the embodiment shown below is the same as that shown in FIG. 9 of the conventional example, and the frame format used in this system is the same as that shown in FIG. 10 of the conventional example. Since it is the same as that shown in FIG. 1, a redundant explanation will be omitted, and the same elements shown in the figure as in the conventional example will be described with the same reference numerals.

FIG. 5 is a block diagram showing control station 1 and station 3,
Receiving section 20. Transmission unit 30. Frame control unit 40, transmission/reception control unit 50, line switching interfaces 60-1, -60
-n, a CPU 70, and a memory 80.

The receiving section 20 extracts a clock from the serial data on the transmission path and outputs the received clock and received data to the frame control section 40. The transmitter 30 receives the transmit data and transmit clock from the frame controller 40, and transmits serial data synchronized with the transmit clock onto the transmission path. The frame control section 40 detects frames from the received data manually inputted via the reception section 20 and outputs control data such as parallel data and slot numbers to the transmission/reception control section 50.

The transmission/reception control unit 50 allocates parallel data input from the frame control unit 40 to ports corresponding to slot numbers. At the time of configuration, the CPU 70 sets the start time slot number and end time slot number of the control area in a register in the control section. Also, the start time slot number and end time slot number of the circuit switching area are set in the circuit switching interfaces 60-1, . . . 60-n. Also, during the operation (line connection or release operation) described later, a table containing information on transferring data between buffers of the line switching interface is set based on information of a control packet received via the control channel transmission/reception control unit 502. do. The memory 80 stores a control program for operating the CPU 70 and a table showing time slot occupancy information and allocation status to each station.

The line switching interfaces 60-1, . . . , 60-n perform line switching between each station (between terminals accommodated in each station) using the line switching area on the frame. The circuit switching interfaces 60-1, . . . 60-n have a transmission/reception buffer for accommodating data in the circuit switching area for transmission/reception with the transmission/reception control unit 50, and a transmission/reception buffer on the terminal side, and transmit data between the buffers. It consists of a table containing transfer information. Line switching interface 60-1,...
60-n associates time slots and terminals based on the information in this table and realizes the above line switching.

FIG. 6 is a block diagram showing the detailed configuration of the transmission/reception control section. This transmission/reception control unit will be described in detail since it is a part that realizes two access methods for a plurality of channels in the control area and is the main component of the present invention.

The transmission and reception control unit includes a control channel transmission and reception memory 501, a control channel transmission and reception control unit 502. Delay circuit section 503. It consists of a selector section 504.

The control channel transmission/reception control unit 502 performs packet communication of control data using the control area on the frame. The control channel transmission/reception control unit 502 constantly monitors the control area, and if it detects a packet addressed to its own station, it receives it, and if there is transmission data, it sends an empty packet (an area indicating empty/busy information in the bucket format is set in the packet). Detects and transmits the data (empty/occupied control). Packets received addressed to the local station are passed to the CPU 70 via the control channel transmission/reception memory.

Furthermore, the control area and data communication area that are not addressed to the local station are output to the selector section 504 as they are. In addition, the selector unit 50 responds to a transmission request from the circuit switching interface 60.
4 to control transmission data from each circuit switching interface 60.

During the timing of the control region, the selector unit 504 selects a signal from the control channel transmission/reception control unit 502 as transmission data, and in response to a transmission request from each circuit switching interface 60, selects a signal from each circuit switching interface 60 and transmits it. Data.

The delay circuit section 503 generates a delay similar to the delay occurring in each line switching interface 60 and the like.

The control channel transmission/reception memory 501 stores packets received using channels in the control area and passes them to the CPU 70 , and the CPU 70 writes the transmission packets to the control channel transmission/reception memory 501 , and the control channel transmission/reception controller 502 sends them to the frame controller 40 .

FIG. 7 is a block diagram showing a detailed configuration of the control channel transmission/reception control section 502, including a reception control section 601, a transmission control section 603. Control area detection circuit 605, CRC check circuit 607. Destination address detection circuit 609. Packet type detection circuit 611. Shift register 613, 615, 61
7,619° selector 621,623. Control channel registers 625.627. Control channel frame header generation circuit 629. Source address generation circuit 631° comparator 633. It is constituted by each circuit of the CRC generation circuit 635.

A CRC check circuit 607 detects a CRC error in data and notifies the reception control section 601 of the detected CRC error.

Further, the CRC generation circuit 635 calculates a CRC and adds it to the data.

The destination address detection circuit 609 monitors the destination address area in the packet format at the timing when the reception control section 601 generates the signal, and when it detects its own address, it notifies the reception control section 601.

The packet type detection circuit 611 notifies the reception control unit 601 and the transmission control unit 603 of the packet type in the packet type display area in the packet format at the timing when the reception control unit 601 generates the packet type.

A source address generation circuit 631 generates a source address.

The comparator 633 performs a comparison at the timing of the source address area generated by the transmission control unit 603, and notifies the transmission control unit 603 if a match is found.

The control channel frame header generation circuit 629 generates a frame header at the timing when the transmission control section 603 generates the frame header.

The selector 1 switches the route of the received data under the control of the reception control section 601.

The selector 2 switches the route of the transmission data under the control of the transmission control section 603.

The comparator 633 compares the source address generated by the source address generation circuit 631 with the source information area in the packet format, and notifies the transmission control unit 603 if they match. That is, reception of a packet transmitted by the own station is detected.

Each shift register 613, 615, 617, 619 latches data at word clock timing.

A control channel frame header generation circuit 629 generates a control channel frame header under the control of the transmission control section 603.

The control area detection circuit 605 sets the start slot number and end slot number of each channel in the control channel registers 625 and 627 during system configuration. Here, since the control channel registers 625 and 627 are provided for each control channel, it is possible to set control channels of different bands.

Control channel frame header generation circuit 629 sends data to empty/busy information area, packet type display area, destination information area, and source information area under instructions from control channel transmission/reception control unit 502.

The reception control unit 601 controls each circuit shown above and controls the C
Sends and receives status to and from the PU 70.

The transmission control unit 603 controls each circuit shown above and
Sends and receives status to and from the PU 70.

The above-mentioned control station and stations have the configurations shown in FIGS.
0 (a control program for operating the CPU 70 is stored in the memory 80). The operation will be explained below.

FIG. 8 is a diagram for explaining the calling operation in this embodiment.

When a connection request is made from a terminal accommodated in station 3-1 to a terminal accommodated in station 3-2, station 3-1 searches for an empty slot from the time slots assigned to itself, and when an empty slot is detected. A call request is made to station 3-2. If the called terminal accommodated in station 3-2 is not in use, station 3-2 returns to station 3-1.
Answers incoming calls. Calling terminal of station 3-1 and station 3-1
After the above sequence is completed, the called terminal performs communication using the searched time slot. Note that the sequence shown here is shown only when the line connection is normally terminated.

The above connection control information is sent and received using the channel of the control area 11. In addition, control information between stations, such as configuration information at the time of system startup, is transmitted and received using the channels in the control area 11.

Before explaining the operation of the channel access method in the control area 11, packet formats in the two access methods are shown in FIGS. 3 and 4.

FIG. 3 shows the packet format of the first access method. The packet of the first access method includes an empty/busy information area 901, a destination information area 902, a source information area 903,
It consists of an information area 904.

The empty/busy information area 901 is an area indicating whether the channel is in use (blocked) or not in use (empty). The destination information area 902 is an area indicating the address of the destination station of the packet. The transmission source information area 903 is an area indicating the address of the transmission source station.

The information area 904 is an area for transferring information between stations or between terminals.

FIG. 4 shows the packet format of the second access method. The packet of the second access method includes an empty/busy information area 905, a destination information area 906, a source information area 907,
It consists of a packet type display area 908 and an information area 909. The empty/busy information area 905 is an area indicating whether the channel is in use (blocked) or not in use (empty).

The destination information area 906 is an area indicating the address of the destination station of the packet. The transmission source information area 907 is an area indicating the address of the transmission source station. Packet type display area 908
is an area that displays whether the packet is a single packet, first packet, intermediate packet, or final packet. The information area 909 is an area for transferring information between stations or between terminals.

Next, the operation of the channel access method in the control area 11 will be explained using the flowcharts of FIGS. 1 and 2.

FIG. 1 is a flowchart of a first access method for the control area 11.

FIG. 1(a) is a reception flowchart of the first access method. The control channel transmission/reception control unit 502 constantly monitors the channel, and if the empty/busy information area 901 is occupied (step 101) and the destination information area 902 indicates the own station (
Step 102), performs reception processing (Step 10)
3). The contents of the reception process are the reception buffers 601 and 602.
Copy the packet to CPU 7 and confirm that there is received information.
0 and terminate the reception operation.

FIG. 1(b) is a transmission flowchart of the first access method. The CPU 70 stores the transmission information in the transmission buffers 604 and 605, and issues a transmission request to the control channel transmission/reception control unit 502 (step 104). When the control channel transmission/reception control unit 502 detects an empty packet (step 105), it performs a transmission process to send transmission information to the channel (step 106). After that, the sender information area 9
The empty/busy information area of the channel where 03 indicates the own station is set to be empty. In other words, release the control channel that has gone through the loop once (
Step 107).

FIG. 2 is a flowchart of a second access method for the control area.

FIG. 2(a) is a reception flowchart of the second access method. The control channel transmission/reception control unit 502 constantly monitors the channel, and if the empty/busy information area 905 is occupied (step 201) and the destination information area 906 indicates the own station (
In step 202), reception operation A is entered. Here, if the packet type is a single packet (step 203), single packet reception processing is performed (step 205). The content of the single packet reception process is to copy the packet to the reception buffers 602 and 603, notify the CPU 70 that there is reception information, and end the reception operation. Furthermore, if the packet type is the first packet (step 203), the first packet reception process is performed (step 204). The content of the first packet reception process is to copy the packet to the reception buffers 602 and 603. After receiving the first packet, receive operation B
to move to. In reception operation B, the control channel transmission/reception control unit 502 monitors the same channel, and the empty/busy information area indicates that it is occupied (step 206), and the destination information area indicates the own station (step 207). If the packet type is an intermediate packet (step 208), intermediate packet reception processing is performed (
Step 209) Go to reception operation B again. Also, if the packet type is the final packet in reception operation B (
Step 201), the process moves to reception operation C. Intermediate packet reception processing involves copying information in the information area 909 of the packet to the reception buffers 602 and 603. In reception operation C, final packet reception processing is performed (step 210
). The final packet reception process is performed by the reception buffer 602.60.
This involves copying the information in the information area 909 of the packet to B, notifying the CPU 70 that there is reception information, and terminating the reception operation. In addition, in receiving operation B, if the empty/busy information area 905 is empty or the destination information area 906 indicates another station, this means that an error such as a lost packet has occurred, and the error is notified to the CPU 7G. Report (step 211).

FIG. 2(b) is a transmission flowchart of the second access method. When there is a transmission request from the circuit switching interface 60 or the CPU 70 (step 221), and the empty/busy information area 902 is empty (step 222), the control channel transmission/reception control unit 502 shifts to a transmission operation. During the transmission operation, the CPU 70 uses the transmission buffers 604 and 605.
If the packet set to is a single packet (step 223), single packet transmission processing is performed (step 2
24) Release the control channel (step 224a).

Single packet transmission processing refers to the operation of transmitting the transmission information set in the transmission buffers 604 and 605 to a channel, and then emptying the empty/busy information area 905 of the channel whose transmission source information area 907 indicates the own station. Also, in the sending operation, C
If the packet set in the transmission buffer 604 or 605 by the PU 70 is the first packet (step 22
3) Perform the first packet transmission process (step 225)
. First packet transmission processing is performed by transmission buffers 604 and 605.
Refers to the operation of transmitting the transmission information set in the channel to the channel. Further, after performing the first packet transmission process, the process moves to the transmission operation E. In the transmission operation E, the transmission buffer 6
The intermediate packet transmission process is repeated until the final packet of 04.605 is attached to the set part (step 226) (step 227).The intermediate packet transmission process transmits the transmission information set in the transmission buffer 604.605 to the channel. In the transmission operation E, when the final packet of the transmission buffer 604, 605 reaches the part set, the final packet transmission processing is performed (step 2).
28) Release the control channel (step 229). The final packet transmission process transmits the transmission information set in the transmission buffers 604 and 605 to the channel, notifies the CPU 70 that the transmission has ended, and then sends the transmission information area 907 indicating the own station to the empty/occupied channel. Refers to the operation of emptying the information area 905. Intermediate and final packet empty/full information area 905, destination information area 906, source information area 90
7. The packet type display area 908 is automatically added by the transmission control unit 603.

The control channel transmission/reception control unit 502 performs the operations of the above two access methods.

Thus, in this embodiment, the first access method is selected for things that require quick transmission, such as connection control information, and long information, such as configuration information for each station at the time of system startup, is transferred. In such a case, by selecting the second access method, two control information paths with different properties can be provided. Therefore, connection control information can be transmitted quickly. Furthermore, since orderliness is ensured on both sides of transmission and reception, it is possible to handle long data without complicating procedures and circuits. In other words, the band of the control area can be used efficiently.

Furthermore, if the amount of information differs depending on the type of control information, efficiency can be further improved by setting multiple channels in different bands. Therefore, it is possible to provide a loop communication method that can be applied to large-scale networks.

[Effects of the Invention] As explained in detail above, the present invention provides a loop communication method that efficiently utilizes control information, provides quick response to devices connected to the system, and is adaptable to large-scale networks. can be provided.

[Brief explanation of the drawing]

1 and 2 are flowcharts showing the operation of an embodiment of the present invention, FIGS. 3 and 4 are packet format diagrams in the first and second access methods, and FIG. 5 is a diagram showing the configuration of the station. 6 is a block diagram showing the configuration of the transmission/reception control section 50, FIG. 7 is a block diagram showing the configuration of the control channel transmission/reception control section 502, FIG. 8 is a sequence diagram showing the calling operation, and FIG. The figure is a schematic configuration diagram of a loop communication system, and FIG. 10 is a frame format diagram. Applicant Nippon Telegraph and Telephone Corporation Applicant
Toshiba Corporation Agent Patent Attorney Satoshi Suyama - (Su) (b) 1st Portion Figure 2 (1)) Figure 3 Figure 40 Figure 5 Figure 9

Claims (1)

[Claims] A control station and a plurality of stations are connected in a loop via a transmission path, and the control station transmits a frame having a control area and a data communication area divided into a plurality of time slots. The control information packet is transmitted between the stations using the control area, and the time slot of the data communication area is allocated as a communication path between the terminals accommodated in each station to perform data communication. In the loop communication method, the control area is divided into a plurality of channels, and an access method that monopolizes the channel until the transfer of the control information is completed, and an access method that limits the monopoly of the channel to one round of the loop. A loop communication method characterized by having two types of access methods.